Gut health and your weight, mood and immune system

Originally written for, published 21 August 2018

The impact of gut health on overall health has become more prominent lately as scientists are learning more about its role. It’s no longer thought of as just the thing that digests and absorbs your food, its becoming more recognised as a player in other aspects of health like supporting your immune system, influencing mood and behaviour, producing certain vitamins and hormones and affecting your weight.

Within the gut, you’ll find trillions of bacteria and microbes – around 1-2kg – collectively known as the microbiome. There are more bacterial cells in your body than human cells and it’s reported that there’s up to 1000 species of human gut bacteria, all with different roles in the body. Your individual microbial make up as is unique as your fingerprint.

Along with around 100million neurons in your gut lining (more neurons than in your spinal cord), controlling blood flow, secretions to help digest food and carrying information to the brain, there’s a lot going on in your gut.

Dr Jeffery Gordon, of the Washington University School of Medicine, was one of the first researchers to link intestinal bacteria and obesity states a diverse mix of gut bacteria is the key to staying lean.

Studies have shown that lean people generally have up to 70% more gut bacteria and more diverse gut bacteria than overweight people. A typical Western diet that’s high in fat and refined sugars but low in fibre generally leads to less microbial diversity.

Your microbial makeup can affect how different foods are digested and determines the calories and nutrients your body absorbs. Dietary fibre is digested by certain gut bacteria, producing chemicals that benefit gut health and affect weight loss. Your gut bacteria can also influence how fats are absorbed and your sensitivity to insulin, both of which impact how fat is stored.

Certain gut bacteria influence the production of leptin and ghrelin, the hormones that control your appetite and your drive to eat.

While your gut microbiome is to some extent affected by genetics, the following lifestyle and dietary habits can help to promote more beneficial microbes over harmful ones.

  • Increase fibre intake to encourage healthy gut bacteria like bifidobacteria which can help weight loss. Most high fibre foods, like fruit, vegetables and wholegrains, also contain prebiotics which your gut bacteria break down for fuel to promote more beneficial bacteria.
  • Focus on a variety of wholefoods for a more diverse microbiome. The typical Western diet is usually quite limited, and it’s estimated 75% of the world’s food is made form 12 plant and 5 animal species.
  • Increase polyphenols, a type of antioxidant that your microbiome breaks down to help make more healthy gut bacteria. Polyphenol rich foods include green tea, dark chocolate, olive oil and wholegrains.
  • Eat fermented foods like yoghurt, sauerkraut, kimchi, kombucha and kefir which contain probiotics and healthy bacteria that promote can control the amount of disease-causing bacteria in the gut.
  • Find ways to reduce chronic ongoing stress as it slows gut function. Gentle exercise likes Vinyasa yoga, walking in nature, meditation, breathing exercises or mindfulness techniques can help.
  • Turn off your devices and get quality sleep. Without enough sleep, immunity is lowered, inflammation increases, and gut function slows down.